It is of course better to read data from a memory faster in a shorter time. In particular when the memory stores a program, a quicker read leads to a quicker start of the program execution. The high-speed read from a memory is especially useful in a mobile phone, as a memory of the mobile phone stores executable format programs and commands that can be read and executed directly. Meanwhile, a method for reading and executing an executable format program directly from a memory without copying it into a RAM or the like is called XIP (eXecute In Place).
For a faster data read from a memory, burst transfer is generally performed to enhance data transfer efficiency. For example, in burst transfer, a memory interface circuit accesses the memory to acquire a predetermined amount of data collectively in response to a read request from a CPU. The acquired data spans a plurality of addresses starting from an address specified by the read request. The acquired data is transferred to the CPU.
It has been conventionally practiced that the memory interface circuit controls a process of reading from a memory by switching between a normal read operation and a burst read mode, whereby an average memory access time is shortened.
Patent Literature 1 discloses a technique in which a burst access is controlled based on the difference between an addressing mode of a bus master and an addressing mode of a memory.